Localization ofd-Aspartic Acid in Elongate Spermatids in Rat Testis (original) (raw)

1998, Archives of Biochemistry and Biophysics

Asp level was also seen with immunostaining. ᭧ 1998 In the current study, localization of D-aspartic acid Academic Press (D-Asp) in rat testis was studied by immunohistochem-Key Words: D-aspartic acid; D-aspartate; D-amino ical and biochemical techniques. Immunohistochemiacids; immunohistochemistry; testis; epididymis; MAA cal staining of this tissue using specific polyclonal anti-(methoxyacetic acid); EDS (ethane dimethane sulfobody to D-Asp revealed D-Asp immunoreactivity (IR) nate); rat. in the cytoplasm of germ cells, especially around the region rich in elongate spermatids, the most mature of the germ cells. Weak IR was also noted in cytoplasm of spermatocytes and round spermatids; however, it It has long been believed that only L-enantiomers of was negligible in interstitial cells and Sertoli cells. The amino acids occur in nature and D-amino acids have intensity of immunostaining in each seminiferous tubeen regarded as ''unnatural isomers'' or laboratory arbule differed according to its distinct germ cell compotifacts (1). However, owing to progress in analytical sition. In testis of young rats, seminiferous tubules methods, various D-amino acids have been found, eilack elongated spermatids, and D-Asp was found to be ther in a free form or as a component of protein, in both localized in spermatocytes, the most mature populavertebrates and invertebrates (2, 3). The presence of Dtion of germ cells at that age. We used various toxiamino acids in mammals was first reported in 1965 by cants to destroy specific testicular cell populations Hoeprich who detected D-alanine in the sera of guinea and to confirm the localization of D-Asp in rat testis. Administration of ethane dimethane sulfonate in-pigs and mice (4). Since then, many researchers have duced a selective destruction of all Leydig cells in this demonstrated the existence of various naturally octissue. This resulted in a significant decrease in the D-curring D-amino acids, especially D-serine (Ser) 2 and D-Asp level, which was probably due to a drop in testosaspartic acid (Asp) in mammals. terone brought about by this treatment, and this was D-Ser is known to be present in serum, urine, brain, followed by a modulation of spermatogenesis. Three and peripheral tissues of humans and other mammals days after treatment with methoxyacetic acid (MAA), (5-10). Hashimoto et al. (10) reported that D-Ser is many seminiferous tubules were found to lack or to present at a high level in rat cerebrum throughout posthave severe depletions of pachytene spermatocytes, natal life, compared with other regions of the brain but not of elongate spermatids. This caused reductions or peripheral tissues. He also demonstrated by HPLC in protein content and in the total amount of L-Asp, analysis that the distribution of D-Ser in rat brain is but not that of D-Asp. Twenty days after treatment closely correlated with the distribution of N-methyl-Dwith MAA, the depleted population of germ cells proaspartic acid (NMDA) subtypes of glutamate receptors gressed through the spermatogenic cycle from pachy-(11). This is of interest because stimulation of NMDA tene spermatocytes to elongate spermatids. At this time, the level of D-Asp decreased significantly, as did that of L-Asp and protein, consistent with D-Asp local